Ias on a Grief PB is quite meaningless besides aesthetics if it's being used on a smite/zealer since a 30% ias roll and lvl 20 fanatacism will reach the last breakpoint. For Grief BAs, you might want to invest in higher IAS ones as unlike PBS, they require additional IAS to reach their breakpoints and for barbs without fanatacism, IAS bps are harder to reach.